Flowerbeds are surrounded by stones and earth tiles, but it is far from necessary to clear all of them. Assess the field in the very beginning: it may already have favorable combinations that can create power-ups. Your main goal is to destroy the upper stones and get access to flowerbeds. Making matches in the lower part of the field can be quite useful as they will cause the earth tiles to travel down revealing the flowerbeds.
Each 3 matches or explosions next to a flowerbed make it produce 4 flowers on the field. However, it’s best to leave the flowers to fill up the field and then collect them with a Rainbow Blast or power-ups.
Try not to forget about the drops as collecting them is another goal of the level.